v5.1.0.3
Glycine data from LIS
Type | Domain |
Description | Methionine synthases catalyse the the final step of methionine biosynthesis. Two apparently unrelated families of proteins catalyse this step: cobalamin-dependent methionine synthase, which catalyses the transfer of a methyl group from N5-methyltetrahydrofolate to L-homocysteine and requires cobalamin as a cofactor (MetH; 5-methyltetrahydrofolate:L-homocysteine S-methyltransferase; ) and cobalamin-independent methionine synthase, which catalyses the transfer of a methyl group from methyltetrahydrofolate to L-homocysteine without using an intermediate methyl carrier (MetE; 5-methyltetrahydropteroyltri-L-glutamate:L-homocysteine S-methyltransferase; ). These enzymes display no detectable sequence homology between them, but both require zinc for activation and binding to L-homocysteine. Organisms that cannot obtain cobalamin (vitamin B12) encode only the cobalamin-independent enzyme. Escherichia coli and many other bacteria express both enzymes [ ]. Mammals utilise only cobalamin-dependent methionine synthase, while plants and yeasts utilise only the cobalamin-independent enzyme.The N-terminal half and C-terminal half of MetE in E. coli show some sequence similarity, indicating that the metE gene has evolved from an ancestral metE gene by duplication [ ]. This entry represents a the C-terminal domain of cobalamin-independent methionine synthase (MetE) from bacteria and plants, which contains the zinc ion responsible for binding and activating homocysteine []. It also includes archaeal proteins where this domain corresponds to the entire length of the protein []. |
Short Name | Met_Synth_C/arc |